說明

• 上一篇: MVC實現之四
• 這一篇主要介紹:
  • 項目中用到的Sequelize庫中的一些方法,參考使用Sequelize連接mysql
  • 將Model層加入Mar類中

---

Service層

• 還是從業務出發,Service層是調用方,調用方式和Controller層調用Service層一樣

class Service {constructor(app) {const { model } = app;Service.prototype.model = model;}async index() {const model = Service.prototype.model;let data = awati model.index();data.age = 20;data.remarks = `forever 18`;return data;} }

---

Mar類

• 設計原則是,在不同層之間傳遞參數,通過Mar類.
• 故需要在Mar類中掛載Model
• 改寫Mar類如下

class Mar {constructor(conf) {this.$app = new koa(conf);this.$router = new koaRouter();this.model = new Model(this); // 這一行是新加的this.service = new Service(this);this.controller = new Controller(this);this.router = new Router(this);}listen(port){ /* 未改變 */} }

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Model類 - 初始化

• 新建Mar類如下

class Mar {constructor ( app ) {console.log('Model ok');}test() {return 'Model for Service'}async index() {return {name: 'marron'}} }

• 此時啟動服務器,訪問http://localhost:3000
  

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Model類-操作數據庫

• 準備數據庫,按照docker-compose.yml構建容器.
• 瀏覽器打開管理頁面
  
  注: 密碼是example
• 新建數據庫 marron
  
  
• 準備就緒后,連接數據庫,并測試

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連接數據庫

• Sequelize庫提供的接口如下

const sequelize = new Sequelize('marron', 'root', 'example', {host: 'localhost',dialect: 'mysql' }) sequelize.authenticate().then(() => {console.log('Connect has been established successfully.');}).catch(err => {console.error('Unable to connect to the database:', err);});

• 寫到Model類里面

進入Model類的時候,連接到數據庫

有一個testSQL方法用于測試,連接數據庫是否成功

class Model {constructor(app) {this.connect();}connect(){this.sequelize = new Sequelize('marron', 'root', 'example', {host: 'localhost',dialect: 'mysql'})}testSQL() {this.sequelize.authenticate().then(() =>{console.log('Connect has been established successfully.');}).catch(err =>{console.error('Unable to connect to the database:', err);})} }

看到這句話時,說明數據庫連接成功了

---

表模型

• sequelize提供的接口如下

const User = sequelize.define('user', {// 屬性firstName: {type: Sequelize.STRING,allowNull: false},lastName: {type: Sequelize.STRING},{// 參數} });

• 加到Model層的addTableUser中

class Model{addTable = {user: async () => {const User = this.sequelize.define('user', {// 屬性name: {type: Sequelize.STRING,allowNull: false},date: {type: Sequelize.DATE,defaultValue: Sequelize.NOW}});// 同步到數據庫User.sync({ force: true })}} }

• 然后在Model的構造函數中調用一次

class Mode {constructor(app) {this.addTable.user();} }

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插入一條數據到表中

• 首先要有User表的結構
• 暫時寫在Model類的User方法中

class Model () {constructor(app) {}User() {return this.sequelize.define('user', {// 屬性name: {type: Sequelize.STRING,allowNull: false},date: {type: Sequelize.DATE,defaultValue: Sequelize.NOW}})} }

• 寫添加user的方法
• 寫在add屬性下面

class Model () {add = {user: async (person) => {const User = this.User();User.create(person);// 同步新增用戶this.sequelize.sync();}} }

然后在constructor里面運行一次this.add.user({name:'marron'})

查詢數據

class Model {find = {user: async () => {const User = this.User();return await User.findAll();}} }

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給Service提供服務

• 前面完成了連接數據庫、創建表、往表內插入數據、查詢數據的接口
• 下面就是在Model中寫一個index方法,給Service層中let data = awati model.index(); 提供服務

class Model () {async index() {return await this.find.user();} }

---

總代碼如下

const koa = require('koa'); const koaRouter = require('koa-router');class Mar {constructor(conf) {this.$app = new koa(conf); // 相當于koa的實例this.$router = new koaRouter(); // 相當于koa-router的實例this.model = new Model(this);this.service = new Service(this);this.controller = new Controller(this);this.router = new Router(this);}listen(port) {this.$app.listen(port, async () => {console.log(`[mar]Server is running at http://localhost:${port}`);})} }class Router {constructor(app) {const { controller, $router, $app } = app;$router.get('/', controller.index);$app.use($router.routes());} } class Controller {constructor(app) {const { service } = app;console.log('Controller:', service.test());Controller.prototype.service = service;}test() {return 'Controller for Router'}async index(ctx) {const service = Controller.prototype.service;ctx.body = await service.index();} } class Service {constructor(app) {const { model } = app;Service.prototype.model = model;}test() {return 'Service for Controller'}async index() {const model = Service.prototype.model;let data = await model.index();data.age = '20';data.remarks = 'forever 18';return data;} }const Sequelize = require('sequelize');class Model {constructor(app) {this.connect();}// 給其他層的測試函數test() {return "Model for Service"}// 連接數據庫的函數connect() {this.sequelize = new Sequelize('marron', 'root', 'example', {host: 'localhost',dialect: 'mysql'})}// 測試是否連接成功testSQL() {this.sequelize.authenticate().then(() => {console.log('Connect has been established successfully.');}).catch(err => {console.error('Unable to connect to the database:', err);});}async index() {return await this.find.user()}addTable = {user: async () => {const User = this.sequelize.define('user', {// 屬性name: {type: Sequelize.STRING,allowNull: false,},date: {type: Sequelize.DATE,defaultValue: Sequelize.NOW}});User.sync({ force: true })}}User() {return this.sequelize.define('user', {// 屬性name: {type: Sequelize.STRING,allowNull: false,},date: {type: Sequelize.DATE,defaultValue: Sequelize.NOW}});}add = {user: async (person) => {const User = this.User();User.create(person);// 同步新增用戶this.sequelize.sync();}}find = {user: async () => {const User = this.User();return await User.findAll();}} }module.exports = Mar;

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